In article .com,
Andy
Evans wrote:
The advantage of a tube stage is that the output with DC on it can be
fed directly into the grid of the tube, and the DC included in the
biasing.


Are you claiming this is impossible for non-tube stages? JLS

Bad choice of words - I can see what you mean. Let me rephrase "it's
convenient to go directly into the grid because you don't need a
coupling cap at this point". You're the expert at ss, and I'd be
delighted to see a schematic for a ss solution with no coupling cap.

IIUC what you are saying the equivalent would be to connect the DAC output
directly to the gate of a FET or base of a transistor, in either case
operating as a gain stage/buffer like the valve. Then fit a dc break cap
following it, just like the valve. Hence so far as I can see there is no
'advantage' for valves here. And it could be just as 'convenient' with
SS devices - if that was what you wanted to do.

Publish the valve circuit you have in mind and I or someone else can
probably give one for essentially the same topology using a SS gain
device.

BTW regardless of valve or SS I would not personally follow a DAC directly
with a gain device. I'd be quite likely to include a passive LPF regardless
of the type of gain device. But perhaps not everyone would bother to do
this, and nothing to do with type of gain device per se.

Slainte,

Jim

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